1. Field of the Invention
This invention relates to elevating and supporting apparatus capable of raising or lowering an object or person to a desired height and thereafter rigidly supporting same at that height. The invention also relates to methods for assembling such apparatus.
2. Description of the Prior Art
It is often necessary to support an object or person at an adjustable height and, in many instances, it is necessary that the object or person be supported firmly and solidly without any wobble or play in the supporting mechanism. One example of such requirement may be found in the construction of dental chairs wherein a mechanism in the base is formed for moving the seat structure upwardly or downwardly to the desired height. Any looseness or play in the supporting mechanism causes the chair to wobble, resulting in the patient feeling uneasy and uncomfortable.
Manufacturers of dental chairs have spent large amounts of money in developing and manufacturing mechanisms capable of lifting, lowering and supporting the patient with the required degree of solidity. Among the more popular of these methods are the mounting of the seat structure on a hydraulic ram, or upon a massive scissors jack, or upon a member mounted in sliding guideways and moved vertically as by a rack and gear assembly. In each of these alternatives, the main problem is solidiy of support, and this problem is usually solved by expensive precision machining to close tolerances of the various surfaces which are in sliding contact with each other.
Similar problems are encountered in other fields, such as elevatable work platforms for electricians working on overhead wires and lights, where precision in lifting and lowering, and solid support at all heights, is essential.